1. Field of the Invention
This invention relates to a simulator for automatic vehicle transmission controllers.
2. Description of the Related Art
As a simulator for automatic vehicle transmission controllers, it is known to analyze the behavior of the hydraulic pressure of a 5-speeds automatic vehicle transmission with planetary-gear set (AVEC′ 94; October in 1994). Also, it is known to use a simulator named “Hardware In the Loop Simulation” (HILS) which incorporates an Electronic Control Unit (ECU) mounted on a vehicle with the simulator (manuscript No. 983 of the conference held on May in 1998 held by Society of Automotive Engineers of Japan). Thus, there have hitherto been proposed simulators which analyze the shift control algorithm.
In automatic vehicle transmissions, the clutch (frictional engaging elements) has a clearance where hydraulic fluid (oil) flows in and out. Since the clearance is occupied with a mixture of fluid and air, the clearance becomes a kind of black box or a dead volume. Accordingly, in order to accurately analyze the behavior of the clutch including a play-removing clutch piston stroke for removing the play in the clearance, the simulator sampling time (interval) must be set to a quite short time such as 1 μsec. As a result, the simulator must repeat calculation most frequently and hence, it needs much time to simulate even one shifting (gear shifting).
Further, even if it becomes possible to ideally model the behavior of a clutch including its play-removing clutch piston stroke, the model can only be applied to the clutch modeled and would not be applied another clutch that is different from the modeled one.
For these reasons, no conventional simulator for a controller of an automatic vehicle transmissions having frictional engaging elements such as clutches, can simulate shift control algorithm stored in the controllers and evaluates the same in a time equal to that of a real shift (gear shifting) or even in a time close thereto.
Furthermore, there is a need of a general-purpose simulator for a controller of an automatic vehicle transmissions having frictional engaging elements, which can simulate shift algorithm stored in the controllers in a constant time for different frictional engaging elements. However, there has not hitherto been proposed such a general-purpose simulator.
Aside from the above, in order to conduct a durability (life) test of an automatic transmission and to evaluate the quality of the product, an automatic transmission for testing is usually built and a preliminary test is conducted thereon. Then, the transmission is placed on a bench and is connected with an internal combustion engine of a vehicle on which the transmission is mounted. The bench test is continued for relatively long period of time (e.g. several months).
Thus, it has hitherto taken much time and costs to develop a new automatic transmission including cost for building the transmission for testing. In particular, since the development of a new automatic transmission must be paced with that of other components of the vehicle, the conventional testing leaves much to be improved in the efficiency of development.